Fuel pump



July 14,l 1942. W. A. WOOD FUEL PUMP Filed Jan. 2, 1941 Patented July 14, 1942 UNITED STATES PATEN T oFFlcE FUEL PUMP Walter A. Wood, Detroit, Mich.

Application January 2, 1941, Serial No. 372,704

(Cl. S-,44)

Z'Claims.

The present invention relates to pumps particularly designed to move fluid fuel for automotive` internal combustion engines, from the such as a oat bowl in which a float controls theV inflow of liquid fuel. But, because of the usually small capacity of such float bowls, the valve operated by the oat is incapable of withstanding very high pressures.

The problems, therefore, confronting the designer of fuel pumps include that of elevating the fluid fuel variable distances, dueto the departure of the vehicle from a truly horizontal position, the delivery of such fuel to the carburetor under a pressure less than that required to force open the float controlled valve, and the meeting of the variable demands for fuel by the engine under changing'load conditions. p

Among the objects of lthe present invention is to overcome the Vobjections to many of the forms of pumps intended to solve the above problems and provide a structure which will deliver a l suiiicient quantity of fuel under all conditions at such a pressure as will permit an easy, even flow into the carburetor without danger of flood Vis indicated as comprising a body member 20.

provided at one end with an inlet conduit 2|, the outer end of which isthreaded to enable the connection of suitable tubing (not sliown) leading from a fuel tank (also not shown). The inner or other end of conduit 2| opens through a boss 22 to the under face of body 20, the boss projecting.. substantially centrally of a seat` 23 upon which is secured, with the interposition of a gasket 24, a settling chamber 25.

chamber 25 isa screen element 26, this being dished as shown to permit the projection intoM the upper part of the chamber to some distance, of an outlet tube 21 to thereby form a gasfor air lled pulsation cushioning chamber above the liquid in the settling chamber.

The outlet tube 21 from chamber 25 is a part y of the inlet conduit 30 for the pump proper and forms a seat for pump inlet valve 3| opening against a spring 32 acting against and guided by a plug 33.

Conduit 30 leads to a pump chamber 35 formed in the pump body 25, and shown as a concavity on the underside of the body, and over which is secured a exible diaphragm 36 which, in turn -is covered by a reversely concave cover plate 3l having a substantially centrally located boss 38 into which is secured a tube 36 communicating with a pulsating means such as is shown in Figure 2. Cover plate 31 is also provided with a lateral boss 31a into which is secured a plug 31h having a capillary passage 3`|c, the purpose of which will be described later. Leading from chamber 35 is a short tube 45 forming apart of outlet valve 4l which is substantially the same as valve 3|. y

Conduit 46 and its continuations lead to the point of discharge (usually a carburetor) and in order to properly regulate such discharge, it is preferred to insert in this conduit a pulsation dampener and also a pressure regulator.

The dampener ,is indicated at 5B and shown as a small chambered element opening downwardly into conduit 46, while a suitable form of pressure regulator is shown to the right thereof in this figure. This form of regulator consists of a short tubular continuation 5| of conduit 46" having a cross tube 52, closed at one end 53 and flared at the other to produce a fairly large dished ange 54 over which is secured a exible diaphragm 55 pressed toward conduit 5| by a spring 56 mounted in a suitable cap 51 provided with a small opening 58. 'Ihe diaphragm 55 carries a plug member 56 lying inl the cross tube 52y and loosely fitting therein and provided with a circumferential groove 6| arranged to be in line normally with the bore of tube 5|. When back pressure develops in the delivery conduit, fluid passes along the plug body to the underside of diaphragm 55 and lifts the latter and, of course, the plug 60, thereby partially or entirely cutting off flow through the jconduit, by virtue of the groove 6| being moved out of registry with the passage or bore.

Surrounding the boss 22 and covering the 55 Referring now to Figure-2, this shows a pump involving substantially th'e same elements as that o! Figure 1, excepting the back pressure regulator. In this gure, the settling chamber and its associated screen, inlet valve, etc., is the same in form and function as that already described and will be designated as a whole as 25. The same similarity of construction exists in the pump` chamber 35, outlet valve i-ili, outlet passage 4 88 and chamber element E6.

The pump body, however, contains a second chamber 15, for convenience located -irl alignment with pump chamber and of lenticular shape. This chamber 151s divided by a diaphragm, conveniently an extension of the pump diaphragm, and the upper portion communicates through a passage 'il with outlet passage e6.

' Coacting with the underside of diaphragm 'it is a valve member 1S which is cylindrical and is provided with an annular groove normally registering, or substantially so, with the passage 39a,

-valve the passage 38a and, in order to permit free movement, it is necessary to provide for balancing the pressure in the small chamber or space under diaphragm E5 and in the tube 88. This may be accomplished by providing a passageway 18a connecting the two spaces, either through the member 'i8 as shown or through the pump body.

'I'his valve member 'l and its associated operating parts serve also as a back pressure regulator in that pressure developing in passage 56 causes depressionof diaphragm i6 and thereby moves valve member 'i8 downwardly so as to throttle or substantially entirely cut on passage of pulsations through passage 39a to the pump chamber.

Also set into a wall of passage 39a is a plug 31c similar to the plug 31o in Figure 1 and for the same purpose.'v In this form of pump as well as in the others shown, including Figure l, al-

ready described, pulsations of alternating inf movement by a suitable cam 8| on the camshaft 88. The outward return of the piston 80 is accomplished by means of a spring 92 acting between ange 86 and a suitable flange or'cover plate or both 93 on the projecting end of piston While the relative proportions of the cylinder 85, tube 39h (bore and length) are not critical, it is necessary that they be such that the piston substantially completely displaces the air from the cylinder 85 into the tube 39h and pump to produce a quite high pressure therein and, conversely, when the piston moves outward to permit a quick drop to sub-atmospheric pressure.

Further, the tube 39h may -be suiliciently long to enable the pump to be located away from the engine to avoid undue heating, and of suiciently large. bore to avoid undue internal friction, not, however, so. large as to materially reduce the pressure transmitted to the pump diaphragm. Satisfactory results have been obtained with a pump capacity of twenty gallons per hour at 2000 R. P. M. engine, speed in using a pulsating cylinder of 11/2 inches bore and el; inch stroke what diierent form of pulsator is used. ln this form, the fuel pumping diaphragm is indicated at |35 with the r imp chamber at |36, all of the fuel passages, valves, etc. being in theupper part |31 of the structure and not being shown. Below the diaphragmv |35 is a dished plate |48 having in its center an opening Uil allowing communication between the space below the diaphragm and a pulsating chamber |135, in the bottom of which is a second diaphragm fixed at its center to an actuating rod ifil and constrained against flexure, except at or near the edges, by metal plates |58 and |139. Both diaphragms |35 and ||6 are sealed at their edges by the flanges |50, screws |5|, and the edge of the intermediate plate |60. l

The upper end of the rod Wi is guided in a suitable spider or perforated plate |52 which also serves as an abutment for a spring |53 acting against a iiange |54 and tending to thrust the rod |41 downwardly. A small opening |55 serves to vent the chamber under the diaphragm |46.

In the edge of plate which is suiciently thick for the purpose is a sma-llpassageway |60 enlarged in its outer portion to receive a threaded plug |6| also provided with a passage which may be formed by providing the threaded shank with a flat side and notching the underside of the head, as indicated at |62. This passageway opens to the outside air from chamber and corresponds to passage 31e in Figs. l and 2. By making the notch |62 suitably small and the :dat side of the screw shank of suitable proportionate size, the passage so produced vmay be regulated in size from that lprovided by the notch when the screw is tight.

Mention has been made above of the capillary passage 31o opening from the atmosphere into the air passages of the pumps shown in Figures 1 and V2. The term capil1ary" as applied to the passage 81o is intended to mean only that it is .of quite small diameter but not of microscopic because of the high wall friction and, therefore, the action of the rapid iluctuation of pressure due to the movement of piston 9H or diaphragm |46 upon the pump diaphragm is not materially ailected. i l

A second function of the passage 31o, more or less incidental to the rst, is that of ventilation so ythat no condensation can take place within the air passages.

A third function, applicable particularly to the pump of Figure 2, is that of bleeding the pressurefrom passage-39a when the valve I8 has closed.

The present case is in part a continuation of gines, a pumping diaphragm, an air chamber of which said diaphragm forms a wall, a second movable wall for said chamber, means for moving said second wall to thereby `compress and decompress air in said chamber, and means for permitting air to pass in or out ofsaid chamber, said means including acontinually open capillary passage extending laterally from the outside air to the air chamber between the said movable walls.

2. In a fuel pump for internal combustion engines, a pumping diaphragm, an air chamber of which said diaphragm forms a wall, a second movable wall for said. chamber, meansfor moving said second wall to thereby compress and decompress air in said chamber, means for permitting air to pass in or out of said chamber,

.said means including a continually open capillary passage, and means for adjusting the size oi said passage.

WALTER A. WOOD. 

